Which measure is most directly related to reducing vulnerability?

The implementation of firewalls is directly related to reducing vulnerability because firewalls serve as a critical barrier between trusted internal networks and potentially untrusted external networks. By controlling incoming and outgoing network traffic based on predetermined security rules, firewalls can prevent unauthorized access and cyber threats from penetrating an organization's network. This effectively mitigates the risk of external attacks and data breaches, addressing vulnerabilities that may exist in the system.

In contrast, while strategic user training is important for creating aware and informed users who recognize security threats, it does not directly eliminate vulnerabilities within the system itself. Cost analysis of security systems focuses on financial considerations rather than directly addressing security posture or vulnerabilities. Incident reporting procedures are essential for identifying and responding to security breaches but do not proactively reduce vulnerabilities; instead, they help organizations learn from incidents to improve future security measures. Firewalls provide that proactive line of defense, making their implementation a direct measure for reducing vulnerabilities.